This study armed to develop a biofilter packed only with fern chips for the removal of air-borne propylene glycol monomethyl ether acetate (PGMEA). The fern chip biofilters could avoid the shortcomings of traditional media, such as compaction, drying, and breakdown, which lead to the performance failure of the biofilters. In the present study, a three stage down-flow biofilter (2.18 m in height and 0.4 m¡Ñ0.4 m in cross-sectional area) was constructed for the performance test. The first stage serviced as a humidifier for the incoming gas and the following two stages, both packed with fern chips of 0.30 m ¡Ñ 0.40 m ¡Ñ0.40 m, as trickling bed biofilters for the VOC removal. The experiment was divided into four phases. Operation conditions of an empty bed retention time (EBRT) of 1.60min and influent PGMEA concentrations of 9.33-329 (average 78.4) mg/m3 were used in the Phase I experiment which lasted for 99 days. An average PGMEA removal of only 68% was obtained in this phase. For improving the PGMEA removal in the following phases, a fixed dosage of milk powder of 1.0 g/(m3 media. day) added as aqueous milk suspension was added to the media for nutrition of the biofilms on the fern chip surfaces. After an additional operation time of 20 days (the 127th day from the startup time), a stable PGMEA removal of 91% was achieved. Following Phase II, PGMEA removals of 93 and 94% were obtained with EBRTs of 0.40 and 0.27 min, respectively, in Phases III and IV experiments. The results indicate that EBRT was not a key influencing factor to the PGMEA removal as long as the media had a high ability for the VOC degradation. Experimental data obtained from Phases II-IV reveal that with volumetric loadings (L) of less than 250 g PGMEA/(m3.h) to the up-streaming half of the whole media, 90% of the influent PGMEA could be removed in this half media. An additional 80% of the influent PGMEA to the following half media could be removed with L < 100 g PGMEA/(m3.h) to the half media. The PGMEA elimination capacities were proportional to the volumetric loadings of less than 250 g PGMEA/(m3.h). From the results, it could be proposed that for achieving over 93% of the PGMEA removal, appropriate operation conditions are media moisture content = 52-65%, media pH = 7.2-7.4, influent PGMEA concentration = 100-400 mg/Am3, EBRT = 0.27-0.40 min, and L to the whole media = 45-180 g PGMEA/(m3.h).